1. Field of the Invention
The present invention relates to a vibration damping bushing used for vibration damping connection, for example, between a suspension arm and a vehicular body in an automobile suspension mechanism. The present invention also relates to a method for manufacturing the same.
2. Description of the Related Art
Conventionally, in an automobile suspension mechanism and the like, a vibration damping bushing has been disposed at a connecting portion between a suspension arm that supports wheels and a vehicular body, and the suspension arm and the vehicular body are connected in a vibration damping fashion via the vibration damping bushing. One example of the vibration damping bushing is disclosed in Unexamined Japanese Patent Application Publication No. JP-A-2003-294084, for example, wherein an inner axial member to be mounted to the vehicular body is inserted through an outer cylindrical member fitted into the mounting cylinder of the suspension arm, forming a structure consisting of these inner axial member and the outer cylindrical member connected in a vibration damping fashion by a main rubber elastic body in a cylindrical form.
The vibration damping bushing described in JP-A-2003-294084 is provided with a stopper mechanism for limiting relative displacement between the inner axial member and the outer cylindrical member in the axial direction for the purpose of improving running stability of the vehicle and securing durability of the main rubber elastic body. More specifically, a stopper member is press-fitted onto the inner axial member, and the stopper member is adapted to abut against the mounting cylinder of the suspension arm, thereby providing a first stopper mechanism that limits relative displacement of the inner axial member against the outer cylindrical member to one side in the axial direction.
However, since the stopper member constituting the first stopper mechanism is fitted into the inner axial member only by pressing, it is difficult to secure enough resistance force to prevent the stopper member from slipping out in the axial direction. Therefore, if the stopper member is hit hard by the mounting cylinder of the suspension arm due to an input of a shockingly large load, the stopper member may possibly be displaced off the inner axial member to the other side in the axial direction, thus creating a risk that the stopper effect in the axial direction by the first stopper mechanism would not be exerted stably. As a result, there were some occasions when targeted running stability of the vehicle or durability of the main rubber elastic body could not be obtained sufficiently.